Volcano 40 miles east of Mexico City rumbles back to life

Popocatépetl has begun belching smoke and ash, possibly signaling a major eruption.

Popocatépetl, the nearly 18,000 foot volcano straddling the border of Puebla and Morelos states in central Mexico, has started a series of small eruptions, which could presage something more violent. And that could be a serious problem, since it's the second highest peak in Mexico, looming above the plain about 40 miles east of Mexico City within sight of about 30 million people. For the last 11 days, it has been venting gasses and tossing rocks as far as a mile from its cone.

NASA's Geostationary Operational Environmental satellite, the GOES-13, captured a short video of gas and ash flowing from the volcano.

Mexican authorities have set up shelters to gather residents for evacuation, should that become necessary. Local residents have begun wearing paper filtering masks.

Popocatépetl, whose name comes from the Nahautl for "smoking mountain," sits six miles above a 35 million cubic foot magma chamber and is connected by a saddle to another volcano, Iztaccíhuatl. Since the arrival of the Spanish in the 16th century, it has erupted over a dozen times, including an expulsion of hot rock in 2000 that forced the evacuation of tens of thousands.

At a press conference, CENAPRED Director Roberto Quaas told reporters, including the Washington Post, that "scientists have no way of predicting whether the molten rock in the chamber will be slowly released, or erupt in a powerful explosion."

In addition to the threat to people in the path of any potential explosion, the havoc it would cause in Mexico City (one of the world's largest cities) could be tremendous.

The 1980 eruption of Mt. St. Helens in Washington State brought Spokane, a city of 200,000 located 350 miles away from the volcano, to a stand-still for months. It clogged the streets with ash that would cloud whole blocks with the passing of a single car. The eruption caused respiratory problems, limited air traffic, and damaged vehicle engines beyond use.

By comparison, Mexico City, the country's capital, has a population of nine million and is 40 miles away from Popocatépetl. A major explosion would shut down, or at least severely curtail the efficiency of, every governmental function, from law-making to law enforcement to communications and trade.

For now, however, few measures are being taken. State officials told the Latin American Herald Tribune that the parade to celebrate the 150th anniversary of the Battle of Puebla, including an estimated 12,000 student marchers, is planned to go on as scheduled on May 5th in that city.

I know that geologic history for volcanoes is not a guarantee of what happens during the next eruption, but if the plains around those cones show a history of regular pyroclastic flows, vs. the more gentle lava flows of a volcano like Kīlauea, then it would be a bad sign.

Hi, just to note that the article's header says: "Popocatépetl, the nearly 18,000-foot volcano straddling the border of Puebla and Moreno states in central Mexico..." but where it says "Moreno" should be "Morelos".

Portland, OR is ~50 miles from Mt. St. Helens but wasn't nearly as affected as Spokane because it wasn't in the path of the prevalent winds. Is Mexico City actually in the likely path of any ash cloud?

The cartels aren't nowhere near there. The center of Mexico is relativity unaffected by the "war on drugs".Some of the people there even think the whole war on drugs thing is an exaggeration of the media to keep people distracted from the "real" problems in Mexico.

Of course those people have obviously never been to the north of Mexico or have any family there.

The cartels aren't nowhere near there. The center of mexico is relativity unaffected by the "war on drugs".Some of the people there even think the whole war on drugs thing is an exaggeration of the media to keep people distracted from the "real" problems in Mexico.

Of course those people have obviously never been to the north of Mexico or have any family there.

It was more of a light hearted joke than anything. But if you consider the passing of drugs from the south to the northern parts of mexico, i would say it would present issues. And some of the corruption that allows the cartel trade to continue could be effected if the capital city is shut down. But then again, with the limited law enforcement abilities, it could allow them to run more rampid in a time where all available resources will be flowing to emergency response.

Just some end of the work day pondering I did after posting my goof of a joke.

I know that geologic history for volcanoes is not a guarantee of what happens during the next eruption, but if the plains around those cones show a history of regular pyroclastic flows, vs. the more gentle lava flows of a volcano like Kīlauea, then it would be a bad sign.

I'm not a volcanologist, but I think a simple indicator of explosive potential is the steepness of the volcano's side slopes. A steeper slope suggests more viscous magma and more viscous magma means that gases can get trapped more easily---thus creating the explosive potential. Wikipedia says that there's a history of pyroclastic flows and lahars, but that would be localized to the immediate area, not necessarily Mexico City. However, prevailing winds in the northern tropics where Popocatépetl is located are Northeasterly (i.e., blowing to the Southwest) so Mexico City could be affected by an explosive eruption.

Portland, OR is ~50 miles from Mt. St. Helens but wasn't nearly as affected as Spokane because it wasn't in the path of the prevalent winds. Is Mexico City actually in the likely path of any ash cloud?

Exactly what I wondered. Interwebs says prevailing wind direction in Mexico City is SW -> NE (lots of hits on this as the direction of the city's air pollution plume, which is infamously sizable, depends on it). The volcano is SE of the city. So mostly likely, but still weather-of-the-moment dependent, plume path is tangental to the city rather than into it.

P.S. This sound somewhat different than the St. Helen’s explosion, which was preceded by mainly steam eruptions rather than actual magma.

"Aren't nowhere near"? You mean the cartels are actually located exactly on top of the volcano? That seems a precarious place to base your HQ. Think of the drive up there, it would take hours, and some people would need oxygen. Granted, in the winter you could ski down.

Portland, OR is ~50 miles from Mt. St. Helens but wasn't nearly as affected as Spokane because it wasn't in the path of the prevalent winds. Is Mexico City actually in the likely path of any ash cloud?

fractalsphere wrote:

Wouldn't the jet stream in that area basically carry the dust away to the east, away from Mexico city?

Yeah, some notes on prevailing wind conditions, any expected major asymmetry in the explosion, and a note on any estimates of stuff like Volcanic Explosivity Index would be helpful in the article. Even the most massive eruptions can show significant directionality in stuff like ash fall. As an example, here's a selected part of the wikipedia 1815 Tambora eruption map showing ash fall. It's not just in a circle around the eruption site.

It refreshes every minute. All the snow and ice melted due to the the volcano's activity.

I can't find accurate information but as far as I remember, the danger areas are small towns around the volcano and the city of Puebla (pop. 2.5 million). The volcano has a uh… I'm not sure how to call it, a dam–like part of the crater that could easily break during an eruption, sending all the lava and stuff to that direction.

The volcanos, that includes Iztaccíhuatl, give some impressive views when the air is clear in Mexico City:

I went on a climbing trip to Mexico in December about 15 years ago and we had to climb Iztaccihuatl instead of Popo since it was active at the time. At the time it didn't have snow at the top even though it was winter. The best thing about climbing Izty was the view of Popo. The route that we took up Izty started near where you would have started for Popo since the company that I went with was originally planning on climbing Popo, it was definitely not the best way up Izty.

I know that geologic history for volcanoes is not a guarantee of what happens during the next eruption, but if the plains around those cones show a history of regular pyroclastic flows, vs. the more gentle lava flows of a volcano like Kīlauea, then it would be a bad sign.

I'm not a volcanologist, but I think a simple indicator of explosive potential is the steepness of the volcano's side slopes. A steeper slope suggests more viscous magma and more viscous magma means that gases can get trapped more easily---thus creating the explosive potential. Wikipedia says that there's a history of pyroclastic flows and lahars, but that would be localized to the immediate area, not necessarily Mexico City. However, prevailing winds in the northern tropics where Popocatépetl is located are Northeasterly (i.e., blowing to the Southwest) so Mexico City could be affected by an explosive eruption.

That's rather simplified, but essentially correct.There are three basic types of volcano:

Cinder cone - The "classic", ultra steep sided type drawn by children that rarely get more than a hundred or so meters high.

Shield - Hawaii type volcanoes with very thin, basaltic lava. They almost never erupt explosively because the magma is (relatively) low in silica and therefore doesn't trap gas well. It also means the resulting volcano will be rather flat but very wide as the thin lava spreads and flows easily.

Composite - Mt. Saint Helens and Mt. Pinatubo are recent examples. Usually these are composed of Andesitic magma (named for the Andes Mountains), which is silica rich and much thicker, which makes it better at trapping gas. It also means the volcano will generally be very large, steep sided, and prone to erupting explosively (Think of what happens when you try to blow bubbles in a milkshake through a straw - It's difficult, the surface heaves as gas pressure builds up, and then at some unpredictable threshold it releases explosively). There will be very little visible lava coming from the eruption - most of it will be ash and pyroclastic flows.

In short, silica content dictates volcano shape and eruptive character, and, grossly speaking - the steeper the volcano the more explosively it will erupt. Most of the volcanoes bordering the "Ring of Fire" (or any subduction zone) will be of the composite type. Hotspot/divergent boundary volcanoes tend to be of the shield type.

While I'm not even remotely inclined to go live on an active volcanic island, if I had to, I'd pick someplace like Hawaii or Iceland over someplace like the Philippines for precisely these reasons. They're far less likely to just go *BOOM* someday.

Wouldn't the jet stream in that area basically carry the dust away to the east, away from Mexico city?

Whatever is left over..........yes.

The jet stream is a high-altitude entity. According to Wikipedia, subtropical jet streams don't start until 33,000 feet, cruising altitude for a jetliner. The dust that eventually makes its way up there should be carried away. But any dust that hangs around below that altitude is probably going to have an effect that's a lot more local.

Portland, OR is ~50 miles from Mt. St. Helens but wasn't nearly as affected as Spokane because it wasn't in the path of the prevalent winds. Is Mexico City actually in the likely path of any ash cloud?

15 or so years ago it had the same symptoms, only that time everything was coated with about 1 or 2 mm of ash where I live, about 70 miles away.

Oh, just an FYI: Mexico city was founded on a island located in small lake on a valley. Which means some areas are slowly sinking into the ground (specially the massive stone buildings made by spaniards over massive pyramids below) and air cannot get to flow freely, thus causing the pollution problems we know.

"Aren't nowhere near"? You mean the cartels are actually located exactly on top of the volcano? That seems a precarious place to base your HQ. Think of the drive up there, it would take hours, and some people would need oxygen. Granted, in the winter you could ski down.

Has Bond taught you nothing? The top of a volcano is the *perfect* location for a cartel's HQ

Don't understand that comment. Mayans live in the south-east of Mexico, as any fule kno.Mexico City folks - Chilangos - are in theory at least the descendants of Aztecs, Spaniards; the billionaire class are mostly of Lebanese ancestry.

I am from Puebla, the state that usually takes the tall on the ashes dropped from the popocatepetl. It is a beautiful sight whenever there is an eruption. 40 miles might not seem like a lot, but it's basically enough to make the eruptions almost harmless.

The volcano started erupting again at the very end of 1995 I believe, it was scary then because it was new t me. Since then it has been going on and off every couole of years. Right now I kinda like looking at it... Though it's rather annoying being an asthmatic or cleaning a car these days.

-- Now if only those mayans could shut up... Don't understand that comment. Mayans live in the south-east of Mexico, as any fule kno.Mexico City folks - Chilangos - are in theory at least the descendants of Aztecs, Spaniards; the billionaire class are mostly of Lebanese ancestry.

Curt Hopkins / Curt writes for Ars Technica about the intersection of culture and technology, including the democratization of information, spaceships, robots, the theatre, archaeology, achives and free speech.